Most current cabs, for instance, on tractors for bulldozers and the like, are locked from the outside using a key. The locks are such that they cannot be unlocked or operated from inside the cab when locked.
There are some locks which are key locked on one side and have a mechanism on the other side for unlocking. For example, U.S. Pat. No. 2,682,763, issued to Williams on July 6, 1954, shows a garage door latch which is key locked from the outside but has a slide mechanism on the inside which can be actuated on the inside to release the latch. Also, U.S. Pat. No. 1,908,958, issued to Coffron on May 16, 1933, shows a door latch which can be released from the inside and can have the bolt disconnected from the outside handle so that the outside handle will turn without moving the bolt.
A door lock assembly which is known to have a key lock on the outside and a lever on the inside for operating the assembly is used in some heavy equipment cabs today. This assembly has a lock release lever which extends into the cab and may be manually pivoted back and forth between locked and unlocked positions. The lower body of the lever has a notch in which an ear may be received to lock the outside handle from turning and has a cam surface which causes the lever to pivot to an unlocked position when engaged by a shoulder while the inside handle is turned. However, the slot in the door through which the lever extends is relatively long and is only partially blocked by the lever, the remaining portion being open. Thus, dust and other particles are allowed to get into the lock assembly with a potentially deleterious effect thereon.
The present invention is directed to overcoming one or more of the problems as set forth above.